Composite Nano-tio <sub> 2 </ Sub> / Zno Preparation And Photocatalytic Performance Study

Nanosized TiO₂ has excellent photocatalytic activity to degrade most of pollutants and has developed to be the novel treatment technology. The most important focus has been on the improvement of photocatalytic activity and the decrease of costs of production. The researches has proved that semiconductor-compounding has the possibility of activating its visible-light activity and that recyclable photocatalyst has the possibility of reducing costs.The complexity of spatial distribution of environmental pollution, the limitation of application of various sorts of nano-TiO₂ photocatalyst and the irreplaceable function of every sort of nano-TiO₂ photocatalyst spotlighted that researches on different sorts of nano-TiO₂ should be concerned. In this thesis, herein, 0-0 composite nano-TiO₂/ZnO and 0-2 composite nano-TiO₂/ZnO were prepared by sol-gel method. The structure, shape and spectrum characteristic were characterized by XRD, FE-SEM, EDS, FT-IR and UV-vis. Being taken chloramine phosphorus, one sort of organophosphorus pesticides, as the model compound of photocatalytic reaction, the effect of photocatalytic activity was analysed by tailoring process parameters. The degradation of organic substance was studied from the perspective of dynamics.The pure nano-TiO₂ and composite nano-TiO₂/ZnO powder were prepared by sol-gel method. The results indicated that the particle size of TiO₂/ZnO powder was varied with the change of composite ratio of ZnO and the particle augmented with the increasement of annealing temperatures. To compound appropriate amount of ZnO was instrumental in generating the structure of mixed-grain.TiO₂ nanotubes were prepared by anodizing Ti in different electrolytes and TiO₂/ZnO nanotubes were prepared by the self-assembly of ZnO-sol. The influence of operation parameters on their morphology was discussed. The results indicated that morphology of TiO₂ nanotubes was different when regulating anode voltage, oxidation time, electrolyte composition etc. The aggrandizement of nanotube's diameter was determined by the 'mergers' of original nanotubes and the length of TiO₂ nanotubes was determined by the balance between the electrochemical reaction rate and chemical dissolution rate. The morphology of nanotubes was affected a little by compounding appropriate amount of ZnO, which did not affect the formation of TiO₂ crystalline. The compounding also expanded the excitation wavelength of TiO₂ nanotubes into the range of visible.The photocatalytic activity of 0-0 composite TiO₂/ZnO nano-powder improved dramaticly after compounding appropriate amount of ZnO. The best photocatalytic activity of degrading chloramine phosphorus using TiO₂/ZnO nano-powder could be got under the conditions of 500℃(2℃/min, 1h constant-temperature), molar ratio of TiO₂/ZnO (10:1), 0,6g/L content of photocatalyst, 4.5mg/L original content of chloramine phosphorus solution. While, the photocatalytic activity of TiO₂/ZnO nanotubes did little to improve, which was mainly affected by the structure of TiO₂ nanotube. The weight of Nanotube array film was calculated and the comparison of photocatalytic activities of nanopowder of equal weight and nanofilm of equal area with nanotubes was made at the same time. The study found that the degradation rate(5h) of nanotubes was 3.5 times higher than that of nanopowder and 4.2 times higher than that of nanofilm under the same conditions.